Ferromagnetic nanostructures display intriguing physics and applications in wide areas, including digital memory [1]}, [2]}, information processing [3]}, [4]}, [5]} and biomedicine [6]}. In the smallest ferromagnetic structures, exhibiting a single magnetic domain, the magnetisation reversal occurs through a coherent rotation described by the Stoner-Wohlfarth model [7]}, [8]}. In such systems, the switching time distributions, close to the switching field, are well described by a single exponential with a characteristic time \(\tau \) .
The temperature dependence of \(\tau \)  is well described by the Néel-Brown model [9]}, [10]}, [11]}, [12]}, based on thermal activation, at high temperatures, and quantum tunneling at low temperatures [13]}, [14]}. With increasing size of the nanostructures, the magnetisation reversals occur principally through curling mode involving inhomogeneous rotation of spins or through propagation and annihilation of a vortex or a domain wall.
In a nanowire, the reversal occurs through vortex-pair nucleation and annihilation and the switching time distributions show a stretched exponential decay, with wide switching field histograms. This is attributed to the presence of many parallel minimum energy pathways (MEPs), with different energy barriers, for the vortex.
